Wameyo 436Report 21Menengai Crater2000MT66MT42 MT64 MT62 MT57 MT58 MT65mElevation (m)0-2000-4000-6000184159140122110867164595349454036312723201812512000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000Horizontal distance (m)FIGURE 33: MT resistivity cross-section NW-SEdepth, with the lowest resisitivity to the southwest (< 10 Ωm) <strong>and</strong> the northeast (
Report 21 437 Wameyo7. CONCLUSIONS AND RECOMMENDATIONS• The Menengai geothermal system exceeds 150 km 2 at 1300 m a.s.l. as defined by resistivitystructures.• A low-resistivity cap delineates the geothermal system, showing boundaries in all directionsexcept northwest.• The low-resistivity cap is underlain by a high-resistivity core that reaches an elevation ofapproximately 1750 m a.s.l. close to the northeastern caldera rim.• The existence of a high-resistivity core indicates reservoir temperatures exceeding 240-250°C,provided there is an equilibrium between the temperature in the reservoir <strong>and</strong> the alteration ofthe rocks, as expressed by the resistivity.• Soundings in the northeast part of the survey area indicate the existence of another geothermalsystem, the Solai system. A more extensive survey is needed to verify that <strong>and</strong> to delineate it.• MT resistivity cross-sections show low resistivity at deeper levels that could be related to heatsources.• Major geological structures appear to have a strong influence on the resistivity distribution inthis prospect area, as observed in the MT results.The Menengai prospect appears to host a large geothermal system that can be developed to boostKenya´s power dem<strong>and</strong>. This field could be defined better if more TEM <strong>and</strong> MT soundings were donewest <strong>and</strong> north of the prospect. Additional soundings inside the caldera will also fine-tune the pictureinside the caldera, especially in areas where the low-resistivity cap is not well defined due to large dataspacings.The experience during prospecting for geothermal resource in Menegai area proved that using bothTEM <strong>and</strong> MT has proven to be very quick <strong>and</strong> effective in exploring for geothermal resources. Thesensitivity of <strong>electromagnetic</strong> methods to low resistivity makes it easier for TEM to define thickness<strong>and</strong> depth of low-resistivity caps that are common in high-temperature geothermal systems. MT, onthe other h<strong>and</strong>, is h<strong>and</strong>y in locating <strong>and</strong> defining deep resistivity anomalies such as low resistivityassociated with thermal excitation of conduction in the massive crystalline rock comprising thebasement.ACKNOWLEDGEMENTSI wish to express my sincere gratitude to KenGen for the chance <strong>and</strong> support to participate in thistraining. Also to Martin Mwangi, Silas Simiyu, Zack Muna, Nicholas Mariita, Stephen Onacha <strong>and</strong>the entire KenGen geophysics staff for support during my preparation for the course. I wish to thankour human resources staff Mrs. Beatrice Soy, Mary Gachuhi, Suzy Ogwaye <strong>and</strong> Matthew Chebogelfor their assistance <strong>and</strong> support in granting me study leave <strong>and</strong> getting necessary travelling documents.To the UNU, I am very grateful for the financial support <strong>and</strong> the rare opportunity that you havegenerously given me to gain wonderful knowledge from this course. I wish to express my unreservedappreciation to the UNU-GTP staff, Dr. Ingvar B. Fridleifsson (Director), Mr. Lúdvík S. Georgsson(Assistant director) <strong>and</strong> Mrs. Gudrún Bjarnadóttir for making our stay in Icel<strong>and</strong> comfortable <strong>and</strong> forthe superb coordination of all our training activities <strong>and</strong> excursions. I am greatly indebted to mysupervisors, Knútur Árnason assisted by Dr. Hjálmar Eysteinsson <strong>and</strong> Ragna Karlsdóttir, who are partof ISOR’s geophysics team, for their guidance, sharing knowledge <strong>and</strong> experience with me, not tomention the encouragement they constantly gave me during my specialized course <strong>and</strong> project writeup.I feel honoured to have been your student.Finally, I wish to thank my wife, Phoebe Agufa <strong>and</strong> my sons, Phillip Wameyo <strong>and</strong> Pascal Mudave forenduring my absence, for their encouragement <strong>and</strong> support. May God bless you <strong>and</strong> grant you yourwishes <strong>and</strong> happiness in life.
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